This invention relates to a cartridge filter having a construction for preventing a filter housing from being contaminated when paint or ink is being filtered.
In processes for producing paint or ink, a filter cartridge is generally used to filter the paint or ink immediately before the paint or ink is filled in a vessel such as a can or a drum.
The cartridge filter element cartridge used for this purpose is fixed in a filter housing to separate insoluble material contained in a liquid such as paint by supplying the paint to be filtered into the filter housing while under pressure it and passing the paint from the outside of the cartridge element to the inside of the cartridge element.
Thus, according to this process, the inside of the filter housing is contaminated with the paint. Accordingly, when paint of a different color is filtered through the cartridge filter, the interior of the filter housing must be cleaned. This is not only very troublesome work but disadvantageous in terms of working efficiency and productivity due to an increase in the working steps since the filter housing must be cleaned every time when a number of different colored paints must be filtered.
In order to filter a liquid paint or ink containing a hardener such as a magnetic paint in an in-line, a cartridge filter in which a filtering material is wound on a porous cylinder is mounted in a filter case, and the liquid to be treated is introduced from the inlet of the filter case through a pipe. The liquid is passed from the outside of the cartridge filter element to the inside so as to separate insoluble materials and the filtrate is exhausted from the outlet of the filter case through a pipe.
Therefore, since the inside of the filter housing or case is contaminated with the paint even in this case, the interior of the filter housing must be cleaned when the cartridge filter element is exchanged in the case that the product to be filtered is altered. Further, in the situation of the paint containing the hardener like the magnetic paint, the adhering is immediately hardened when it is contacted with the air. Thus, the task requires brushing or cleaning with a large quantity of solvent. This type of cleaning is extremely troublesome work and is disadvantageous since the working efficiency and the productivity are not raised. In addition, since it is very difficult to clean a long filter case by brushing or cleaning with a solvent, there arises a problem that the length of the cartridge filter which can be used is limited.